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(No Model.)

F. FISHER. TELEPHONE LINE SWITCH. No. 31 L813. Patented Ma 31, 1886.

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UNITED STATES PATENT OFFICE.

FRANK E. FISHER, OF DETROIT, MICHIGAN, ASSIGNOR TO THE DETROIT ELECTRICAL WORKS, OF SAME PLACE.

TELEPHONE-LINE SWITCH.

SPECIFICATION forming part of Letters Patent No. 314,818, dated March 3 1, 1885.

Application filed October 1, 1884. (No model.)

T on whom it may concern:

Be it known that I, FRANK E. FISHER, of Detroit, in the county of Wayne and State of Michigan, have invented a new and useful Improvement in Telephone Line Switches, of which the following is a specification.

My invention consists in a telephone-switch constructed, as hereinafter described, so that the act of securing the connecting-cord thereto in the exchange breaks the groundconnection and the act of removing the connecting-cord restores the ground, so that it is impossible to leave a subscribers line open.

Figure 1 is an elevation, partly in section. Fig. 2 is a perspective. Fig. 3 is a perspective of the spring-plug used for making the connections, and Fig. 4 shows a slightly-different mode of constructing the same switch. A represents a portion of a switch-board in a telephone-exchange.

B represents a metal frame set in and se curely fastened to the switch -board. That part of frame B which lies within the board A is larger than the rest, and has an oblong hole drilled through it, as shown at M in Fig. 1. Nearly all the rest of frame B is cut away, with the exception of its outer end, as shown in Fig. 1, this being left full size, as shown at O, and perforated to permit the passage of a movable piece, D. r

In the cut-away part of frame 13 are set two binding-posts, G H, both insulated from the frame, and between the binding-post H and the end of the frame a lug, F, is raised on the frame to the height of bindingpost H.

D represents a movable piece of metal, one end of which is a cylinder terminating in a round head, with a groove, E, where said head joins the cylinder, the other end being of any convenient shape, but preferably with a flat under surface and adapted to slide through the perforation on part 0 of frame B.

I represents a binding post secured to piece D. r

K represents a metal spring secured to the flat side of D, and bent into such form that it will bear on binding-post H when piece D is in the position shown in Fig.1, and will bear on the lug F without touching bindingpost H when piece'D is moved into the posi- 5o tion shown in dotted lines. The spring K also holds the cylindrical portion of piece D away from the lower side of the hole therethrough, and prevents said piece D from coming in contact with binding-post G, but allows 5 such contact when piece D is pressed toward said bindingpost with enough force to overcome the resistance of said spring. The range of motion of piece D is limited in one direction by contact of spring K with part 0 of frame B, and in the other by the shoulders shown on D coming in contact with the cylindrical part of the frame.

P represents a spring-plug, to one end of which is attached one end of a flexible connecting-cord, Q, the other end thereof being fastened to a similar plug.

L represents the handle of the plug P, made of some insulating materialwood or rubher; and W represents the plug proper, consisting of a hollow metal cylinder adapted to fit over the cylindrical part of piece D, and having a notch, 0, cut therein.

Fastened to the cylindrical part W of the plug is a spring, N, the-end of which is bent .75 into the shape of a U and lies in the notch O.

A subscribers line entering the exchange passes through an annunciator and is connected with binding-post I, and is thus in electrical connection with piece D and frame B, or may be connected with any part of frame B. The binding-post H is permanently connected with the ground, and the binding-post G is connected with the operators telephone and the generator for ringing a call-bell in the 8 5 manner usually employed in telephone-exchanges.

When the subscriber whose line is connected with binding-post. I calls the exchange, the operator who answers the call presses the end 0 of plug 1? over the end of piece D, until the spring N engages in the groove at E. The force necessary to do this pushes piece D into the position shown in dotted lines, and spring K leaves the binding-post H and rests on lug 5 F, so that the subscribers line is no longer grounded in the exchange. By pressing on the plug in a direction at right angles to the axis thereof the piece D is thrown into contact with bindingpost G, and communication established between the subscriber and operator. As soon as the subscriber is put in com- .5 munication with the person wanted, by putting the plug at the other end of cord Q on a switch similar to the one herein described, the operator releases plug P, and the action of spring K breaks the contact between piece D and binding-post G, thus cutting out c o1nmunication with the operator. \Vhen the parties using the line have finished, and the signal for disconnection is given, the operator pulls the plug P off from the piece D; but the spring N holds the parts together until the piece D is moved so that the spring K leaves the lug F and comes in contact with bindingpost H, when the flat part of D strikes against the end of the bored partof frame B, and the plug is pulled off.

The operation of the switch, when constructed as shown in Fig. 4, is the same principle, though the construction details are different. T represents a metal frame secured to the switchboard, corresponding to B.

U and V represent a binding-post and lug corresponding to binding-post H and lug F.

R represents a movable metal piece, corresponding to D, pivoted at Y to frame T, but insulated therefrom, and having secured to one end thereof a spring, S, corresponding to K. The subseribers line is connected to piece Rfthe operators line to binding-post U, and lug V, which is insulated from T, is permanently grounded. When the line is not in use, the spring S is left in contact with lug V. The operation of putting the plug on end X of piece R swings this piece so that spring S leaves lug V, breaking the ground-connection, then comes in contact with bindingpost U, thus making connection with the operators telephone, and finally is swung into the position in Fig. 4, when connection with another subscribers line is male. WVhen the signal for disconnection is given, the with drawal of the plug from the end X of piece 7 R swings this piece so that spring S comes and remains in contact with lug V, this being the limit of the motion of swinging piece R l in that direction.

WVhat I claim as my invention, and desire to secure by Letters Patent, is

1. A telephone-switch consisting of a fixed metal frame having attached thereto, but insulated therefrom, a ground-connection and a binding-post connected with the operators telephone, and of a metal piece movable in said frame, adapted to make contact with the ground-connection when moved in one direction to the limit of its range of motion'and to break this connection when correspondingly moved in the other direction, and having a lateral motion adapted to bring the same in connection with the binding-post connected with the operators telephone, and a spring-plug adapted to engage with or be disengaged from said movable metal piece by the exercise of force snfficien't to slide said metal piece in said frame, substantially as and for the purposes set forth.

2. In combination with the fixed metallic frame B, carrying the insulated binding-posts H G, the movable binding metallic piece D, adapted to slide therein, and carrying the con tact-spring K, and having its end E rounded and grooved, whereby pressure necessary to connect a spring-plug, P, to said movable piece causes the same to slide to the extent of its range of motion in one direction and pressure necessary to withdraw said plug therefrom causes the same to slide in the other direction, substantially as shown and described.

3. The combination of the frame B, having piece 0, lug F, and oblong hole M, and carrying the insulated binding-posts H G, with the movable metallic piece D, having grooved end E and contactspring K, and spring-plug P, substantially as shown and described.

' FRANK E. FISHER. 

